The present invention relates to machines used to build up and tear down mounds of dumped or piled pourable material on a storage field. Typically, such machines comprise a railway-mounted portal-shaped lower framework which spans and rides along the length of a long conveyor belt extending between two parallel row-like mounds, or the locations where such row-like mounds are formed. The conveyor belt has a loop which feeds material to and from the machine. Such machines usually have a pick-up boom provided with a scoop-up unit for tearing down a built-up mound, and a dump boom provided with a dump conveyor for dumping onto the storage field the material received from the conveyor belt system in order to build up a mound. The two booms are typically pivotally mounted, so that they can be raised and lowered. The pick-up boom is usually mounted on a generally C-shaped upper framework which is rotatably mounted on a lower framework provided with railway wheels, the end of the C-shaped upper framework being provided with a counter-weight for balance against the weight of the pick-up boom. The two booms are located diametrally opposite each other.
Federal Republic of Germany published allowed patent application DT-AS No. 1,229,913 discloses a pick-up and dump machine, wherein the dump end of the pick-up-boom is located above the aforementioned loop of the conveyor-belt system, with the dump end of the dump boom located below such loop. In order to counterbalance the weight of the dump boom, the dump boom is coupled to the counterweight boom. The conveyor-belt system which feeds material to and from the pick-up and dump machine must be reversible, and must be reversed in direction when changing over back and forth between pick-up operation and dumping operation. As a result, the pick-up and dump machine can only operate in the pick-up mode or else in the dump mode, at any given time. Furthermore, the height to which the dump boom is raised or lowered is determined by the height to which the pick-up boom is raised or lowered.
Federal Republic of Germany published allowed patent application DT-AS No. 1,281,942 teaches the combination of a pick-up boom and a bucket wheel, for the tear-down of a built-up dumped mound. However, such structure is not well suited when a long row-like dumped mound is to be torn down for materials-mixing purposes.
Federal Republic of Germany published allowed patent application DT-AS No. 1,221,147 discloses a pick-up and dump machine of this type, provided with a generally C-shaped upper framework having an additional counterpoise affording the requisite counterweight action. However, this pick-up and dump machine, likewise, is not capable of operating in both the pick-up and dump modes simultaneously.